Переход на CpuRenderEngine

src/render/CpuRenderEngine.zig

@@ -35,10 +35,43 @@ pub fn exampleReset(self: *CpuRenderEngine) void {
 }
 
 pub fn example(self: CpuRenderEngine, canvas_size: ImageSize, visible_rect: ImageRect) !?dvui.Texture {
-    _ = self;
-    _ = canvas_size;
-    _ = visible_rect;
-    return null;
+    const full_w = canvas_size.w;
+    const full_h = canvas_size.h;
+
+    const width = visible_rect.w;
+    const height = visible_rect.h;
+
+    // Выделить буфер пиксельных данных
+    const pixels = try self._allocator.alloc(Color.PMA, @as(usize, width) * height);
+    defer self._allocator.free(pixels);
+
+    std.debug.print("w={any}, fw={any};\th={any}, fh={any}\n", .{ width, full_w, height, full_h });
+
+    var y: u32 = 0;
+    while (y < height) : (y += 1) {
+        var x: u32 = 0;
+        while (x < width) : (x += 1) {
+            const gx: u32 = visible_rect.x + x;
+            const gy: u32 = visible_rect.y + y;
+
+            const denom_x: f32 = if (full_w > 1) @as(f32, @floatFromInt(full_w - 1)) else 1;
+            const denom_y: f32 = if (full_h > 1) @as(f32, @floatFromInt(full_h - 1)) else 1;
+            const fx: f32 = @as(f32, @floatFromInt(gx)) / denom_x;
+            const fy: f32 = @as(f32, @floatFromInt(gy)) / denom_y;
+            const factor: f32 = std.math.clamp((fx + fy) / 2, 0, 1);
+
+            const r_f: f32 = @as(f32, @floatFromInt(self.gradient_start.r)) + factor * (@as(f32, @floatFromInt(self.gradient_end.r)) - @as(f32, @floatFromInt(self.gradient_start.r)));
+            const g_f: f32 = @as(f32, @floatFromInt(self.gradient_start.g)) + factor * (@as(f32, @floatFromInt(self.gradient_end.g)) - @as(f32, @floatFromInt(self.gradient_start.g)));
+            const b_f: f32 = @as(f32, @floatFromInt(self.gradient_start.b)) + factor * (@as(f32, @floatFromInt(self.gradient_end.b)) - @as(f32, @floatFromInt(self.gradient_start.b)));
+
+            const r: u8 = @intFromFloat(std.math.clamp(r_f, 0, 255));
+            const g: u8 = @intFromFloat(std.math.clamp(g_f, 0, 255));
+            const b: u8 = @intFromFloat(std.math.clamp(b_f, 0, 255));
+            pixels[y * width + x] = .{ .r = r, .g = g, .b = b, .a = 255 };
+        }
+    }
+
+    return try dvui.textureCreate(pixels, width, height, .nearest);
 }
 
 pub fn renderEngine(self: *CpuRenderEngine) RenderEngine {